1. The Field of the Invention
The present invention relates to early prediction of the onset of osteoarthritis, early diagnosis of osteoarthritis, early treatment of osteoarthritis, and screening of drug candidates useful for treating osteoarthritis.
2. The Relevant Technology
Osteoarthritis (“OA”) is the most common joint disease in middle-aged and older people. OA is characterized by joint pain and dysfunction caused by joint degeneration, including progressive loss of articular cartilage, osteophyte formation, and sclerosis of subchondral bone. Joint contractures, peri-articular muscle atrophy, and limb deformity occur in advanced stages of the disease and often lead to disability and sometimes the need for joint replacement. Currently, persistent joint pain and stiffness and radiographic evidence for joint space narrowing, osteophytes, and in some cases, increased subchondral bone density and cysts are used to establish the diagnosis of OA.
OA often develops in the absence of a specific known cause of joint degeneration, a condition referred to as either primary or idiopathic OA. Less frequently, OA develops as a result of joint degeneration caused by injuries or a variety of hereditary, developmental, metabolic, and neurological disorders, which is referred to as secondary OA. Primary OA rarely occurs in people younger than 40 years old. Secondary OA may occur in younger adults. Although a number of risk factors have been proposed to be involved in the pathogenesis of OA, the root causes of primary OA remain unclear. Current treatments for OA, including weight reduction, pain amelioration, and joint replacement, are largely palliative. Efforts to develop methods for the surgical or biological repair of damaged articular cartilage face major obstacles due to the limited intrinsic repair capacity of the tissue. Therefore, the development of novel therapeutic strategies is highly likely to depend upon the identification of the molecular and cellular mechanisms involved in the initiation and progression of OA.